Tides modulate crevasse opening prior to a major calving event at Bowdoin Glacier, Northwest Greenland

• Published in: Journal of Glaciology
• Main Authors: Van Dongen, Eef, Jouvet, Guillaume, Walter, Andrea, Todd, Joe, Zwinger, Thomas, Asaji, Izumi, Sugiyama, Shin, Walter, Fabian, Funk, Martin
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Crevasses; Glacier modelling; Glacier monitoring; Iceberg calving; Bowdoin; Greenland; glacier; Journal of Glaciology; Tidewater
• Online Access: https://risweb.st-andrews.ac.uk/portal/en/researchoutput/tides-modulate-crevasse-opening-prior-to-a-major-calving-event-at-bowdoin-glacier-northwest-greenland(ebbab811-079a-4d80-9227-ef9c92dfe96a).html; https://doi.org/10.1017/jog.2019.89; https://research-repository.st-andrews.ac.uk/bitstream/10023/19382/1/vanDongen_2020_JG_Tides_CC.pdf

Retreat of calving glaciers worldwide has contributed substantially to sea-level rise in recent decades. Mass loss by calving contributes significantly to the uncertainty of sea-level rise projections. At Bowdoin Glacier, Northwest Greenland, most calving occurs by a few large events resulting from kilometre-scale fractures forming parallel to the calving front. High-resolution terrestrial radar interferometry data of such an event reveal that crevasse opening is fastest at low tide and accelerates during the final 36 h before calving. Using the ice flow model Elmer/Ice, we identify the crevasse water level as a key driver of modelled opening rates. Sea water-level variations in the range of local tidal amplitude (1 m) can reproduce observed opening rate fluctuations, provided crevasse water level is at least 4 m above the low-tide sea level. The accelerated opening rates within the final 36 h before calving can be modelled by additional meltwater input into the crevasse, enhanced ice cliff undercutting by submarine melt, ice damage increase due to tidal cyclic fatigue, crevasse deepening or a combination of these processes. Our results highlight the influence of surface meltwater and tides on crevasse opening leading to major calving events at grounded tidewater glaciers such as Bowdoin.